1. Field
The present invention relates to systems and methods for using a reusable apparatus made of shape memory polymer (SMP) to fabricate composite parts.
2. Related Art
Composite parts, such as those used in the manufacture of aircraft, can be constructed using various production methods, such as filament winding, tape placement, overbraid, chop fiber roving, coating, hand lay up, or other composite processing techniques and curing processes. Most of these processes use a rigid cure tool/mandrel on which composite material is applied and then cured into a rigid composite part. Removing the rigid cure tool or mandrel from the cured composite part is generally difficult, costly, and/or time-consuming, particularly if the resulting composite part has trapping geometry that precludes easy part removal. One known method of removing the mandrel requires sacrificing or destroying the mandrel by cutting, dissolving, bead-blasting, or otherwise breaking down the mandrel into smaller pieces which can be removed from within the composite part. Destroying the mandrel obviously prevents it from being used again for subsequent parts and can be damaging to an inner surface of the composite part.
Another method uses a segmented mandrel that can be disassembled and removed after the composite part is cured. However, these mandrels are expensive and require a great amount of time to install and remove. Furthermore, these segmented mandrels are typically each designed to fabricate a specific composite part and are not easily reconfigured to be used in the manufacture of other composite parts.
Yet another method uses inflatable mandrels that can be removed by deflating them after the composite part is cured. However, this method typically involves balloon-like mandrels that can only be used as a bagging aid due to their relative lack of strength and rigidity during composite lay-up.
Another alternative method involves a silicon-coated foam tooling or mandrel. This foam tooling may be covered with a silicon bag and then wrapped with uncured composite material. During cure, the silicon bag is inflated and the foam tooling melts. After cure, the silicon bag may be removed and reused. However, the foam tooling is not reusable, so a new foam tooling must be machined out of new foam each cure cycle.
Accordingly, there is a need for improved methods of fabricating composite parts.